Jarrod Morfett is bigger than most adults but the New Zealand Rugby League says the Waitara teenager is not allowed to play in senior ranks.

"I'm gutted," was all he could say.

Seventeen-year-old Morfett, who weighs 97 kilograms and stands 1.93metres (6ft 4in), has turned out four times this season for the Waitara Bears premier team in the Western Alliance competition.

His club has had competition points for those four games deducted and been fined $400 for allowing an under-age player to play in a premier competition.

The NZRL introduced a minimum age of 18 in senior open grade competitions four years ago on safety grounds.

Morfett, a year 13 Waitara High School student, turns 18 in January.

Morfett hoped the NZRL would grant him dispensation from the age ruling, but NZRL officials yesterday ruled out any chance of that.

Spokesman Kevin Bailey said the age restriction was introduced on the advice from the NZRL medical council.

The ruling states that a player must have turned 18 in the year of the competition, he said.

That means Morfett misses out by just a month, his birthday falling in January.

"It's a safety policy," said Bailey said.

Morfett will stay on the sideline until next month when he can play in a national age group competition. Morfett is also the captain of his school's 1st XV rugby team, but the staunch Melbourne Storm fan admits rugby league is his game.

Waitara Bears coach Stacey O'Carroll admitted he had been aware Morfett was not eligible to play premier grade league due to his age, but put him out on the field only when he was desperate because his team was hard hit this season by injuries or player unavailability.

He said Morfett coped extremely well in the premier games he had played in.

"He was up to it last year.

"He did pre-season training with us this year hoping to play premier football. He started the season playing club under-20s and was scoring two or three tries a game. He's an outstanding prospect for the future."